Multilayer Substrate Gap Elimination via Resin Flow
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Solution Overview
Problem
The existing methods for manufacturing multilayer substrates often result in connection failures between conductive portions of resin layers due to gaps formed during the stacking process, especially when resin layers are arranged in mutually inverted directions, leading to conduction failures and reliability issues.
Innovation Solution
The solution involves increasing the thickness of specific thermoplastic resin layers and ensuring that the interlayer conductive portions are connected without an in-plane conductive pattern in between, allowing the resin to flow and eliminate gaps during press-bonding, thereby ensuring close contact and reducing the occurrence of connection failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If resin layers are stacked in mutually inverted directions to expose conductive patterns at both surfaces, then ease of manufacture is improved, but connection reliability deteriorates due to gaps at interfaces
Solution Approach 1:
The patent changes the physical state parameters of the resin material by controlling temperature and pressure during press-bonding. By heating the resin layers to a temperature where the resin becomes viscous and flowable, and applying sufficient pressure, the resin flows to fill gaps at interfaces between inverted layers, transforming the material state to eliminate voids and ensure reliable conductive connections.
2Ease of manufacture
If conductive portions are made tapered through laser processing, then ease of manufacture is improved, but manufacturing precision deteriorates due to gap formation at interfaces
Solution Approach 1:
The patent utilizes parameter changes in the resin material during press-bonding. By controlling temperature to reach the resin's flow point and applying appropriate pressure, the resin transitions from a rigid state to a viscous flow state, enabling it to fill tapered gaps and interface voids automatically, thereby compensating for the imprecision introduced by laser drilling and ensuring accurate conductive connections.
3Reliability
If resin layer thickness is increased to eliminate gaps, then connection reliability is improved, but productivity deteriorates due to longer press-bonding time
Solution Approach 1:
The patent optimizes the combination of temperature and pressure parameters during press-bonding to achieve rapid resin flow and gap elimination. By heating the resin to its optimal flow temperature and applying sufficient pressure simultaneously, the resin quickly fills interface gaps, achieving reliable connections in a short time without requiring excessive thickness or prolonged processing, thus maintaining high productivity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively reduces the occurrence of connection failures and improves the high-frequency properties of the multilayer substrate by eliminating gaps at interfaces, enhancing reliability and resistance to thermal stress and plating solutions.
Implementation Method 1
a first thermoplastic resin layer 15c, 15d, 15e and a second thermoplastic resin layer 15f press-bonded to one another
Implementation Method 2
the conductive paste is hardened, thereby forming an interlayer conductive portion 14
Data Source
Figure 1~4
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Figure 9~12
AI summary
A multilayer substrate (101) includes a plurality of stacked thermoplastic resin layers each having an in-plane conductive pattern (13) provided on one of principal surfaces and an interlayer conductive portion (14) provided to penetrate through the thermoplastic resin layer in a thickness direction. The plurality of thermoplastic resin layers include a first thermoplastic resin layer (15c, 15d, 15e) and a second thermoplastic resin layer (15f) a stacking direction of which is inverted with respect to a stacking direction of the first thermoplastic resin layer. The second thermoplastic resin layer (15f) is thicker than the first thermoplastic resin layer (15c, 15d, 15e). One of ends in the thickness direction of the interlayer conductive portion (14) formed at the second thermoplastic resin layer (15f) is connected with the interlayer conductive portion (14) of the thermoplastic resin layer (15e) adjacent to the second thermoplastic resin layer in the thickness direction such that the in-plane conductive pattern (13) is not interposed therebetween.